Call to a member function on bool

I'm stuck on validation.
the "validate" instance does not recognize the "hasError" functions:
returning the error:
Call to a member function hasError () on bool

PHP Code:

$validation = $this->validate([
            'user'    =>'required',
//            'mail'    =>'required|valid_email|is_unique[users.mail]',
            'mail'    =>'required|valid_email',
            'pswd'     =>'required|min_length[5]|max_length[12]',
            'cPswd'    =>'required|min_length[5]|max_length[12]|matches[password]'
        ]);


        if(!$validation){
        $usrErr = $validation->hasError('user') ? $validation->getError('user') : "";
            echo 'user: '.$usrErr;                
        }else{
            echo "corretto";    

        } 


after seeing and reviewing several tutorials on the subject, I am at a standstill.

I hope to get help from the experts